AUTOMATIC CONTROL SYSTEM FOR CEILING FAN BASED ON TEMPERATURE DIFFERENTIALS

• US 20100291858A1
• Filed: 07/28/2010
• Published: 11/18/2010
• Est. Priority Date: 02/04/2008
• Status: Active Grant

• Current Assignee: Delta T Corporation (Spectris PLC)
• Original Assignee: Delta T Corporation (Spectris PLC)
• Inventors: Toy, Mark A.
• Granted Patent: US 8,900,041 B2
• Time in Patent Office: Days
• US Class Current: 454/258
• CPC Class Codes: F04D 19/002 Axial flow fans
• CPC Class Codes: F04D 25/088 Ceiling fans
• CPC Class Codes: F04D 27/00 Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids
• CPC Class Codes: F04D 27/001 Testing thereof; Determination or simulation of flow characteristics; Stall or surge detection, e.g. condition monitoring
• CPC Class Codes: F04D 27/004 by varying driving speed
• CPC Class Codes: F04D 27/02 Surge control surge detection F04D27/001
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/56 Remote control
• CPC Class Codes: F24F 11/63 Electronic processing
• CPC Class Codes: F24F 11/76 by means responsive to temperature, e.g. bimetal springs
• CPC Class Codes: F24F 11/77 by controlling the speed of ventilators
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2110/20 Humidity
• CPC Class Codes: F24F 7/007 with forced flow using ducting systems F24F7/06
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
• CPC Class Codes: Y10T 29/49316 Impeller making

Abstract

A fan includes a hub, several fan blades, and a motor that is operable to drive the hub. A motor controller is in communication with the motor, and is configured to select the rate of rotation at which the motor drives the hub. The fan is installed in a place having a floor and a ceiling. An upper temperature sensor is positioned near the ceiling. A lower temperature sensor is positioned near the floor. The temperature sensors communicate with the motor controller, which includes a processor configured to compare substantially contemporaneous temperature readings from the upper and lower temperature sensors. The motor controller is thus configured to automatically control the fan motor to minimize the differences between substantially contemporaneous temperature readings from the upper and lower temperature sensors. The fan system may thus substantially destratify air in an environment, to provide a substantially uniform temperature distribution within the environment.

Claims

1. A fan system installed in a location having a floor and a ceiling, the fan system comprising:

(a) a rotatable hub;

(b) plurality of fan blades secured to the hub;

(c) a motor in communication with the hub, wherein the motor is operable to drive the hub at a selectable rate of rotation;

(d) a motor controller in communication with the motor, wherein the motor controller is configured to select the rate of rotation at which the motor drives the hub;

(e) an upper temperature sensor positioned near the ceiling, wherein the upper temperature sensor is configured to sense the temperature of air near the ceiling, wherein the upper temperature sensor is in communication with the motor controller; and

(f) a lower temperature sensor positioned near the floor, wherein the lower temperature sensor is configured to sense the temperature of air near the floor, wherein the lower temperature sensor is in communication with the motor controller;

wherein the motor controller is configured to automatically adjust the rate of rotation at which the motor drives the hub based at least in part on differences between temperatures communicated from the upper temperature sensor and temperatures communicated from the lower temperature sensor.

2. The fan system of claim 1, wherein the motor controller is configured to compare temperatures communicated from the upper temperature sensor to temperatures communicated from the lower temperature sensor.

3. The fan system of claim 2, wherein the motor controller is configured to automatically adjust the rate of rotation at which the motor drives the hub to minimize differences between temperatures communicated from the upper temperature sensor and temperatures communicated from the lower temperature sensor.

4. The fan system of claim 1, wherein the motor controller comprises a processor and a variable frequency drive.

5. The fan system of claim 4, wherein the upper temperature sensor and the lower temperature sensor are coupled with the processor, wherein the processor is coupled with the variable frequency drive, wherein the variable frequency drive is coupled with the motor.

6. The fan system of claim 4, wherein the processor comprises a Proportional, Integral, Derivative (PID) controller.

7. The fan system of claim 6, wherein the PID is associated with a set value (SV) of zero.

8. The fan system of claim 7, wherein the PID is further associated with a process variable (PV), wherein the process variable represents the difference between a temperature sensed by the upper temperature sensor and a temperature substantially contemporaneously sensed by the lower temperature sensor.

9. The fan system of claim 8, wherein the PID is configured to process errors between the SV and PV values through a PI loop logic.

10. The fan system of claim 1, further comprising a humidity sensor, wherein the humidity sensor is configured to sense relative humidity, wherein the humidity sensor is in communication with the motor controller.

11. The fan system of claim 10, wherein the motor controller is configured to automatically adjust the rate of rotation at which the motor drives the hub based further at least in part on a humidity level communicated from the humidity sensor.

12. The fan system of claim 11, wherein the motor controller is configured to automatically adjust the rate of rotation at which the motor drives the hub using a selected rate of acceleration, wherein the motor controller is configured to select the rate of acceleration based at least in part on the humidity level communicated from the humidity sensor.

13. The fan system of claim 1, wherein the motor controller is configured to provide a first mode of operation and a second mode of operation, wherein the first mode of operation includes a first upper limit on the rate of rotation at which the motor drives the hub, wherein the second mode of operation includes a second upper limit on the rate of rotation at which the motor drives the hub, wherein the second upper limit is higher than the first upper limit.

14. The fan system of claim 13, wherein the first mode of operation further includes a first lower limit on the rate of rotation at which the motor drives the hub, wherein the second mode of operation further includes a second lower limit on the rate of rotation at which the motor drives the hub, wherein the second lower limit is higher than the first lower limit.

15. A method of operating a fan, the method comprising:

(a) providing a fan, wherein the fan comprises;

(i) a rotatable hub,

(ii) a plurality of fan blades secured to the hub,

(iii) a motor in communication with the hub, wherein the motor is operable to drive the hub at a selectable rate of rotation, and

(iv) a motor controller in communication with the motor, wherein the motor controller is configured to select the rate of rotation at which the motor drives the hub,

wherein the fan is provided in a place having a floor and a ceiling;

(b) providing an upper temperature sensor near the ceiling, wherein the upper temperature sensor is configured to sense the temperature of air near the ceiling;

(c) providing a lower temperature sensor near the floor, wherein the lower temperature sensor is configured to sense the temperature of air near the floor;

(d) receiving a temperature reading from the upper temperature sensor;

(e) receiving a temperature reading from the lower temperature sensor; and

(f) adjusting the rate of rotation at which the motor drives the hub based at least in part on differences between the received temperature readings from the upper and lower temperature sensors.

16. The method of claim 15, wherein the act of adjusting the rate of rotation comprises automatically adjusting the rate of rotation to minimize differences between subsequent temperature readings from the upper and lower temperature sensors.

17. The method of claim 16, further comprising:

(a) continuously receiving temperature readings from the upper temperature sensor;

(b) continuously receiving temperature readings from the lower temperature sensor; and

(c) continuously adjusting the rate of rotation at which the motor drives the hub based at least in part on differences between the continuously received temperature readings from the upper and lower temperature sensors.

18. The method of claim 15, further comprising:

(a) providing a humidity sensor, wherein the humidity sensor is configured to sense relative humidity;

(b) receiving a relative humidity reading from the humidity sensor; and

(c) adjusting the rate of rotation at which the motor drives the hub based further at least in part on the humidity reading.

19. A method of installing a fan system in a place having a floor and a ceiling, the method comprising:

(a) coupling a fan with the ceiling, wherein the fan comprises;

(i) a rotatable hub,

(ii) a plurality of fan blades secured to the hub,

(iii) a motor in communication with the hub, wherein the motor is operable to drive the hub at a selectable rate of rotation, and

(iv) a motor controller in communication with the motor, wherein the motor controller is configured to select the rate of rotation at which the motor drives the hub;

(b) installing an upper temperature sensor near the ceiling;

(c) coupling the upper temperature sensor with the motor controller;

(d) installing a lower temperature sensor near the floor; and

(e) coupling the lower temperature sensor with the motor controller.

20. The method of claim 19, further comprising:

(a) installing a humidity sensor; and

(b) coupling the humidity sensor with the motor controller.